1. Technical Field
The invention relates to air spring assemblies for vehicle suspensions. More particularly, the invention relates to an air spring assembly in which one of the bead plates, which is sealingly mounted within an open end of the flexible bladder, has a profile which projects into the air chamber to reduce the volume thereof to increase the spring rate.
2. Background Information
Air spring assemblies typically include one or two end plates or bead plates sealingly connected to respective ends of a hollow fabricated reinforced elastomeric bladder. These air springs are used primarily for implementation in motor vehicles for supporting the vehicle body or for use in other types of equipment subject to shock to provide cushioning therefor. The air springs are sealed at the ends to form a pressurized fluid chamber within the elastomeric bladder. The air spring will generate a certain load at a given height and pressure upon the air spring experiencing a road displacement input and the bladder will begin to collapse or extend as the end members move toward or away from each other to yield predictable dynamic load characteristics.
These dynamic load characteristics of the air spring are a function of the internal air pressure, volume and effective area. For a given height, the effective area is determined by dividing the air spring load by the internal pressure. The effective area and internal volume of an air spring is typically controlled by the maximum inflated diameter and length of the fabric reinforced rubber bladder. The effective volume varies with the air spring height.
For certain applications, it may be desirable to increase the spring rate. One manner of increasing the spring rate of an existing air spring having a predetermined height is to decrease the internal volume of the air chamber within the elastomeric bladder. One previous manner of changing the volume is adding a non-compressible media to the inside of the air spring. However, this could leak or corrode the air spring and contaminate the air system.
Often it is desirable to tailor the dynamic load characteristics of the air spring, such as the dynamic spring rate and natural frequency, to fit a particular vehicle or application. However, it is not always practical to change the bladder size for all applications. For example, some vehicles have certain space limitations which do not allow for a larger bladder size. Also, changing the bladder size may effect other characteristics of the air spring, such as the ride of the vehicle on which the air spring is mounted and the load capacity of the air spring.
Thus the need exists for a simple, inexpensive, yet effective air spring assembly which can increase the spring rate of the air spring without modifying the flexible bladder and which enables a preferred crimp sealing arrangement to be utilized therewith for securing the bladder to the end member or bead plate, which plate is subsequently attached to a spaced component of the vehicle.